<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
   <div id="id1">

   </div>
   <script>
       let id1=document.getElementById('id1');
       id1.innerHTML='<strong>abc</strong>';
   </script>
</body>
</html>